CENTRALIZED LIGHTWAVE WDM-PON EMPLOYING INTENSITY MODULATED DOWSTREAM AND UPSTREAM

• US 20090274462A1
• Filed: 09/22/2008
• Published: 11/05/2009
• Est. Priority Date: 05/01/2008
• Status: Active Grant

• Current Assignee: NEC Corporation
• Original Assignee: NEC Laboratories America Inc (NEC Corporation)
• Inventors: Yu, Jianjun
• Granted Patent: US 8,131,156 B2
• Time in Patent Office: Days
• US Class Current: 398/68
• CPC Class Codes: H04B 10/2587 using a single light source for multiple stations
• CPC Class Codes: H04J 14/0226 Fixed carrier allocation, e.g. according to service
• CPC Class Codes: H04J 14/0227 Operation, administration, maintenance or provisioning [OAMP] of WDM networks, e.g. media access, routing or wavelength allocation
• CPC Class Codes: H04J 14/0246 using one wavelength per ONU
• CPC Class Codes: H04J 14/025 using one wavelength per ONU, e.g. for transmissions from-ONU-to-OLT or from-ONU-to-ONU
• CPC Class Codes: H04J 14/0282 WDM tree architectures
• CPC Class Codes: H04J 2014/0253 Allocation of downstream wavelengths for upstream transmission
• CPC Class Codes: H04L 27/2601 Multicarrier modulation systems

Abstract

An optical system and method includes a source-free optical network unit coupled to an optical fiber for receiving a centralized lightwave carrier signal with downstream data over the optical fiber. The optical network unit includes a coupler configured to split the original carrier signal into a first path and a second path. The first path includes an optical filter configured to reduce fading effects of the carrier signal. The second path includes a modulator configured to remodulate the centralized lightwave carrier signal with upstream data to produce an upstream data signal for upstream transmission.

Claims

1. An optical system, comprising:

a source-free optical network unit coupled to an optical fiber for receiving a centralized lightwave carrier signal with downstream data over the optical fiber;

the optical network unit including;

a coupler configured to split the original carrier signal into a first path and a second path;

the first path including an optical filter configured to reduce fading effects of the carrier signal; and

the second path including a modulator configured to remodulate the centralized lightwave carrier signal with upstream data to produce an upstream data signal for upstream transmission.

2. The system as recited in claim 1, wherein the centralized lightwave carrier includes a plurality of downstream signals multiplexed using wavelength-division multiplexing (WDM).

3. The system as recited in claim 1, wherein the modulator of the optical network unit includes an intensity modulator configured to remodulate the centralized lightwave carrier signal.

4. The system as recited in claim 1, wherein the optical filter includes an optical interleaver configured to convert a double sideband signal into a single sideband signal.

5. The system as recited in claim 1, wherein the optical network unit receives the centralized lightwave carrier as at least a 10 Gb/s intensity modulated orthogonal frequency division multiplexed signal and transmits upstream at least a 1.75 Gb/s on-off keying modulated signal.

6. An optical system, comprising:

an optical line terminal (OLT) configured to modulate a downstream data signal by wavelength division multiplexing on a plurality of orthogonal channels for transmission on a centralized lightwave carrier signal;

a source-free optical network unit coupled to the OLT by an optical fiber, the optical network unit having a modulator configured to remodulate the centralized lightwave carrier signal with upstream data to produce an upstream data signal for transmission back to the OLT, the optical network unit including;

a coupler configured to split the original carrier signal into a first path and a second path;

the first path including an optical filter configured to reduce fading effects of the carrier signal; and

the second path including a modulator configured to remodulate the centralized lightwave carrier signal with upstream data to produce an upstream data signal for upstream transmission.

7. The system as recited in claim 6, wherein the OLT includes an intensity modulator configured to modulate the centralized lightwave carrier signal.

8. The system as recited in claim 6, wherein the coupler splits the centralized lightwave carrier signal in half between the first path and the second path.

9. The system as recited in claim 6, wherein the optical filter includes an optical interleaver configured to convert a double sideband signal into a single sideband signal.

10. The system as recited in claim 6, wherein the modulator of the optical network unit includes an intensity modulator configured to remodulate the centralized lightwave carrier signal.

11. The system as recited in claim 6, wherein the OLT includes a multiplexer to wavelength division multiplex a plurality of intensity modulated channels.

12. The system as recited in claim 6, wherein the optical network unit receives the centralized lightwave carrier as at least a 10 Gb/s intensity modulated orthogonal frequency division multiplexed signal and transmits upstream as at least a 1.75 Gb/s on-off keying modulated signal.

13. The system as recited in claim 6, further comprising a remote node for demultiplexing the downstream signal and multiplexing the upstream signal.

14. A method for providing a centralized lightwave source, comprising:

intensity modulating orthogonal frequency division multiplexed signals for transmission on a centralized lightwave carrier signal;

receiving the centralized lightwave carrier signal by a source-free optical network unit;

splitting the centralized lightwave carrier signal between a first path and a second path;

filtering the centralized lightwave carrier signal on the first path to be received by a user;

remodulating the centralized lightwave carrier signal on the second path with upstream data to produce an upstream data signal for transmission; and

transmitting the upstream data signal.

15. The method as recited in claim 14, further comprising multiplexing a plurality of orthogonal frequency division multiplexed (OFDM) downstream data signals using wavelength-division multiplexing (WDM).

16. The method as recited in claim 14, wherein remodulating includes intensity modulating the centralized lightwave carrier signal with the upstream data signal.

17. The method as recited in claim 14, wherein filtering the centralized lightwave carrier signal includes reducing fading effects.

18. The method as recited in claim 14, wherein filtering the centralized lightwave carrier signal includes optically interleaving the centralized lightwave carrier signal to convert a double sideband signal to a single sideband signal.

19. The method as recited in claim 14, wherein the optical network unit receives the centralized lightwave carrier as at least a 10 Gb/s intensity modulated orthogonal frequency division multiplexed signal and transmits upstream as at least a 1.75 Gb/s on-off keying modulated signal.